James mcnab



2 Sheets-Sheet 1.

J. MoNAB] FURNACE FOR GALGINING BONE BLACK.

in k

Patented 001;. 15, 1889.

mu. ../u v 2 (No Model.) 2 Sheets-Sheqt 2.

J. McNAB.

' FURNACE FOR OALOINING BONE BLACK.

No. 412,781. r Patented Oct. 15, 1889.

N. PETERS. wm-um m wmmmn. n.0,

UNITED STATES PATENT OFFICE.

y JAMES MONAB, OF CAMDEN, NEW JERSEY, ASSIGNOR TO THE UNITED STATESCHEMICAL COMPANY, OF SAME PLACE.

FURNACE FOR CALCINING BONE-BLACK.

SPECIFICATION forming part of Letters Patent No. 412,781, dated October15, 1889. Application filed June 22, 1887. Renewed March 19, 1889. s mino. 303,943. No model.)

To aZZ whom it may concern: p

Be it known that 1, JAMES MoNAB, a citizen of the United States,residing in Camden, county of Camden, State of New J ersey,have inventeda new and useful Improved Furnace for Calcining Bone-Black or AnimalCharcoal, of which the following is a true and exact description,reference being had to the accompanying drawings, which form a part ofthis specification.

My invention has especial reference to the calcining of bone-black oranimal charcoal which has been used for the purification of Sugar, oil,r similar purposes, and which is therefore filled with organicimpurities which must be gotten rid of before the bone-black is fit forfurther-use or treatment; and I have designed this furnace particularlyfor the calcination of the bone-black preparatory. to treating it forthe extraction of acid phosphate of calcium, having also in view theutilization of the surplus heat of the furnace for drying the wetinassesof gypsum and other similar substances which require drying to fit themfor sale or use.

My object is to provide a furnace which will thoroughly calcine theimpure bone-black with the minimum use of fuel, the greatest economy insaving the bone-black, and with provision for the utilization of thesurplus heat of the treatment. Reference is now had to the drawings,which represent afurnace constructed in accordance with my invention,and in which- Figure 1 is a vertical longitudinal section of my furnaceon the line 00 cc of Fig. 3; Fig.-

2, a vertical cross-section, of the furnace and its connections on theline y y of Fig. 1, and Fig. 3 a plan view of the furnace on thehorizontal section to 'w of Fig. 1.

A is the grate or fire-chamber; B B B, fiues opening into thefire-chamber and extending beneath the calcination-chamberlongitudinally until at the extreme end they open into it at B. Theflues B are separated from each other by walls of masonry bl), and uponthese walls and the front and back walls of the furnace C andD theflooring c e of the calcination-chamber E is supported. As shown,

and as I prefer to construct it, the flooring of the chamber E is madeof stone slabs e e, the

tage.

stone, of course, being of a kind which will not disintegrate under theinfluence of heatsuch, for instance, as soapstone. I do not, however,limit myself to the use of a stone floor, as obviously iron or brickmight be used, though not,I believe, with equal advan- F is abridge-wall of masonry or metal.

It forms the end of the calcination-chamber E,

various parts of the chamber E can be regulated.

K is the top of the chamber E, preferably made of arched masonry, asshown.

J J J 2 are settling-chambers situated in, or rather forming, the flueleading from the chamber E to the stack L. They are roofed, like thechamber E, by arched masonry K, though,of course, iron or flat slabs ofstone may, if desired, be used to roof them.

(1 d. d d d, &c., are passages or flue-holes leading from thecalcination-chamber E into the first of the chambers J J J and throughthe walls D from chamber to chamber and into the stack L. The passages dare, as is shown, situated all along the back wall D of the chamber E,and the passages d are also equally distributed along the dividingwa llsD. chambers J J J 2 and the stack L, by means of which they can beopened and cleaned out from time to time.

H represents the bone-black in the calcination-chamber E, and Mrepresents material spread out over the roof of the furnace and chambersJ J J 2 to be dried.

7 j j and Z are man-holes at the ends of the draft in the fire-chamberA.

The dimensions of my furnace may of course be varied to suit the work ithas to do. I have found one in which the calcinationchamber from frontto bridge-wall F was about thirty feet long, having a breadth of aboutsix feet and a height of about three feet and a-half, to give excellentresults.

In operating my furnace, a fire is made in the chamber A, and the flameand gases led through the fines B, beneath the chamber E, into saidchamber at the point B. They then pass through said chamber, into whichair is admitted through openings 0, and escape from it, through thefine-passages d cl, into the settling-chambers J J J and finally intothe stack L. The impure bone-black is introduced into the chamber Ethrough the opening G, and from time to time moved along the flooring eby the operator at the point of entrance. It is not only subjected tothe heat of the hot flooring a, but to the direct action of the flameand gases entering the chamber E over the bridge F, and at this pointabundant air is also admitted to ignite the combustible organic matterin the boneblack, which soon, under these conditions, comes to a stateof high combustion and rapidly frees itself from impurities, and as itis moved back from its point of entrance and exposed to the continuousheat of the chamber E, into which less air is admitted as the capacityof the purifying bone-black to support combustion diminishes,it isfinally withdrawn substantially free from impurities.

By utilizing the impurities of the boneblack as fuel, as beforedescribed, a great economy in coal is obtained; but the draft in thechamber E is necessarily strong, and much of the valuable bone-black iscarried with it into the exit-fines, and the gases thus escaping arevery hot. By passing these gases through the flue-holes d d intochambers J J J and from one such chamber to another before they arepermitted to enter the stack L, the bone-black held in suspension isdeposited in the chambers J J J and the bottom of the stack, and can beWithdrawn for use through the man-holesj I. In passing through thechambers J the gases heat them to a high degree, and any bulkysubstances requiring to be dried can be spread out over the arches K KK, where any moisture will be rapidly driven off. By providingfine-openings d all along the back wall of the calcination-chamber E andconnecting them with the stack I prevent a strong draft from sweepingthrough the calcination-chamber, and thus diminish the quantity ofpowdered bone-black carried out of the chamber, and I also by thisdevice am better able to control the ignition of any part of the blackunder treatment, as when I open a door a the draft is substantially fromfront to back, instead of along the chamber.

My furnace may be modified somewhat. For instance, the fire-chamber Amay be situated beneath the calcination-ehamber E, and where it is notdesirable to use the surplus heat for drying wet material the chambers JJ J may be arranged one over the other and all over the top of thechamber E.

Having now described my invention, whatI claim as new, and desire tosecure by Letters Patent, is

1. In a furnace for calcining and purifying bone-black, the combinationof the fire-chamber A, fines B, passing from the fire-chamber beneaththe calcination-chamber and opening into it at their back end, thecalcinationchamber E, having a feed-opening G at the end where fines Benter it,'doors c in its front wall, and multiple fines d, arranged fromfront to rear along its back Wall, and a stack L, connected with saidfines (I, so as to draw the gases from the back of calcination-chamber Eall along its length.

2. In a furnace for calcining and purifying bone-black, the combinationof the firechamber A, fines 13, passing beneath the calcination-chamber,the calcination-chamber E, having doors 0 in its front wall and fines din its back wall, and a feed-opening G at the end where the fines B openinto it, one or more settling-chambers, and a stack L, connecting withthe fines d d through the settlingchambers, all substantially as and forthe purpose specified.

3. In a furnace for calcining and purifying bone-black, the combinationof the fire-chamber A, fines B, passing beneath the calcination-chamber,the calcination-chamber E, having doors a in its front wall and finesdin its back wall, and a feed-opening G at the end where the fines Bopen into it, one or more settling-chambers lying alongside of thechamber E, and having their roofs K substantially on a level with theroof K of said chamber to form a drying-platform, and a stack L, connectiu g with the fines d d th rough the settling-chambers, allsubstantially as and for the purpose specified.

JAMES MCNAB;

Witnesses:

FRANK A. MULLIKIN, JOSHUA MATLACK, Jr.

